Todd Lipcon created HDFS-4380:
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Summary: Opening a file for read before writer writes a block
causes NPE
Key: HDFS-4380
URL: https://issues.apache.org/jira/browse/HDFS-4380
Project: Hadoop HDFS
Issue Type: Bug
Affects Versions: 1.0.3
Reporter: Todd Lipcon
JD Cryans found this issue: it seems like, if you open a file for read
immediately after it's been created by the writer, after a block has been
allocated, but before the block is created on the DNs, then you can end up with
the following NPE:
java.lang.NullPointerException
at
org.apache.hadoop.hdfs.DFSClient$DFSInputStream.updateBlockInfo(DFSClient.java:1885)
at
org.apache.hadoop.hdfs.DFSClient$DFSInputStream.openInfo(DFSClient.java:1858)
at
org.apache.hadoop.hdfs.DFSClient$DFSInputStream.<init>(DFSClient.java:1834)
at org.apache.hadoop.hdfs.DFSClient.open(DFSClient.java:578)
at
org.apache.hadoop.hdfs.DistributedFileSystem.open(DistributedFileSystem.java:154)
This seems to be because {{getBlockInfo}} returns a null block when the DN
doesn't yet have the replica. The client should probably either fall back to a
different replica or treat it as zero-length.
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